The fundamental operation method of solar power generation is to illuminate sunlight on the surface of solar cells. Currently, in order to increase the power generating efficiency, there are concentrated photovoltaic (CPV) modules, which adopt a Fresnel or plano-convex lens (also called first optical element) for concentrating a great deal of photovoltaic energy. Lessening single size of first optical element and solar cell can shorten focus length and thus thin CPV module. Miniaturization of CPV module can decrease both frame material and cost of transportation.
In practice, secondary optical elements, such as spherical lenses, should be used together with small-area solar cells in the CPV modules for increasing sufficient optical alignment tolerance. Nonetheless, the present method for fixing spherical lenses is difficult and complicated. One of current general secondary optical elements is like glass ball lenses or homogenizer with characteristics of high transmittance and hardness. Another type of secondary optical elements is designed to collect the incident light by reflection, which is called metal collector. If metal collectors are adopted for fabricating secondary optical elements, screw fastening is required for installation, which consumes a substantial amount of labor and components such as screws. On the other hand, if glass ball lenses are adopted, while combining the secondary optical elements with the solar cells on the circuit board, the primary optical encapsulant should be applied first for protecting all surfaces of the solar cells and the metal bonding wires.
Please refer to FIGS. 1A to 1C, which show the schematic diagrams of the method for packaging secondary optical element of solar cell receiver according to the prior art. As shown in the figures, solar cells are first disposed on a substrate 50. Then, gold bonding wires are used for connecting electrically the solar cells with the circuit on the substrate 50. The solar cells 51 and the gold bonding wires are packages on the substrate 50 after curing first optical encapsulant 52.
Next, a particular amount of second optical encapsulant 53 is coated on the hardened first optical encapsulant 52. Then the spherical lens 54, which is used as the secondary optical element, is placed on the second optical encapsulant 53. Afterwards, second is cured and the spherical lens 54 is thus fixed virtually on the solar cell 51.
According to the method described above, while installing the glass secondary optical element, the first optical encapsulant packaging is performed beforehand for protecting all surfaces of the solar cells and the gold bonding wires from damages of down-force pressure of the secondary optical elements. After the optical encapsulant coated in the first time was cured, the optical encapsulant of the second time is applied and the secondary optical elements are placed. Then, the curing process for the secondary encapsulant is performed. Consequently, there are more process steps and time. In particular, the unavoidable double period of curing time is detrimental to mass production.
Accordingly, the present invention provides a novel method for packaging, which enables rapid installation of secondary optical elements in a CPV module onto solar cells as well as lowering the manufacturing cost and complexity. Thereby, the present invention will contribute to the development and promotion of CPV modules.